Process of making cores



Patented June 21, 1932 OFFICE WILLIAM H. WALTER, OF CYNWYD, JPENNSYLVANIA PROCESS OF MAKING (103118 No Drawing.

Hereto fore in making cores for molding metal castings for. foundry work it has been found to be the most practical method, as far as known, to use as a binder for the core sand substances such as oil or molasses in the smaller cores while in large cores flour was often used, the sand being mixed with the binder and packed in a core-box, the core reinforced when necessary by chaplets and stifi'eners, then vented and placed'in an oven to bake, the time required to bake the core being in pro ortion to its size, some very small cores baking in, say, half an hour while others would remainl-in the oven over-night or longer. a 3

This baking process entailed an unnecessary expense and delay, and in making certain types of castings, the cores were not strong enough to withstand rough handlin and broke or became chipped and rendered unfit for use.

The present process or method'has in view the provision of a core which does not re-- ui're baking, is self-venting, and which at t e same time is harder and more rugged than baked cores of the old type and does not require chaplets or stifleners for reinforcing purposes. L g

The present method consists in making a binding agent by mixing a combustible or inflammable compound such as a solution of celluloid with a volatile solvent such as acetone, butanol, etc., forming a paste. The

consistency of the paste is preferably such that it has a very slight tendency to flow and at the same time can be readily handled with a paddle or the like. This binder paste is then mixed with -a suitable grade of core sand in the proportion of from ten to twenty-five percent of paste to the amountof sand re.

quired to make the core.

The solvent will evaporate to such an extent by air drying only and without the use of heat or baking, that cares of about one inch in thickness can be handled roughly in approximately one-half hour and may be used in a mold within two hours after being *made; while the celluloid content of the binder completely burns away durln the casting operation so that the core sand ows Application filed January 20, 1931. Serial No. 510,057.

freely from cored holes and maybe reclaimed. A ,i

Cores made with this type of binder are hard and rugged and capable ofstanding rough usage, maintaining their form over a 55 long span between prints without the use of chaplets or stifi'eners. Furthermore, this process produces a porous core which is self-f venting.

What I claim is: 1 g, 1. The process of making cores of metal castings, which consistsin mixing a solution of celluloid with a 'volatile solvent such as acetone or butanol'to form a paste, and mixing the paste .with core sand in the propora tion of from t'e'n"'to'k'twenty-five percent of paste to sand.

2. The process of making sand articles x ing said binder with sand, then shaping said article from said mixture and permitting said -solvent to evaporate to set sald mixture and form a rigid structure. a W

3.- As an articleof manufacture, a ri id sand article, composed of sand mixed wit a solution of celluloid and a volatile solvent, the sand predominating materially over the celluloid and solvent, and the article being air- 50 dried to evaporate the, major portion of the solvent. p I

1 In testimony whereof, I have hereunto set my hand.

" WILLIAM H. .WALTER. 35 

